As microprocessors have become more complex, they are now often equipped with a debug port. This port is typically an electrical interface that provides access to various parts of the processor circuit. Development engineers can use this port to examine low-level behavior of the processor during run time such as by setting break points, single stepping, and reading debug registers.
The debug port of the processor is often connected to a separate connector provided on the motherboard of a computer, at least during development. This connector allows developers to interface a debug processor or test system to the connector and thereby debug software errors and detect hardware problems as they test initial system software versions.